Respiration,Respiratory pressures,breathing

Question 1

Differentiate between internal respiration and external respiration

Answer 1

a) External respiration::
1) Pulmonary ventilation
2) Exchange of gases
3) Transport of gases
4) Diffusion of gases
b) Internal respiration = cellular respiration:
Intracellular metabolic processes in mitochondria by using O2 & producing CO2

Question 2

Explain the Exchange of gases by the respiratory

system

Answer 2

by diffusion between alveolar air & pulmonary capillary blood.

Question 3

Explain the Diffusion of gases by the respiratory

system

Answer 3

by the CVS, between blood & tissues through systemic capillaries

Question 4

Respiration is divided mechanically into cycles.
Each Respiratory cycle = inspiration + expiration + pause
Normally: …………………. cycles/min.

Answer 4

12-16

Question 5

Give a short note on intra-alveolar pressure.= intrapulmonary pressure

Answer 5

it is the pressure inside alveoli
 During inspiration→ it decreases below atmospheric
pressure→ -1 mmHg = 759 → air rushes in
 During expiration→ it increases above atmospheric pressure → + 1 mmHg = 761 → air rushes out

Question 6

Intraalveolar pressure = O mmHg (= 760 mmHg) at the ……………………………………………………..

Answer 6

end of inspiration & at the end of expiration

Question 7

Intraalveolar pressure always equalizes itself with

………………………………………………….

Answer 7

atmospheric pressure because they are connected

Question 8

Define the intra-pleural pressure= Intrathoracic pressure

Answer 8

it is the pressure between the 2 layers (visceral &

parietal) of pleura

Question 9

During quiet breathing, the intrapleural pressure is ALWAYS ……………………………………

Answer 9

–ve (subatmospheric) & cannot equilibrate with intraalveolar or atmospheric pressures

Question 10

Normal values of intrapleural pressure

Answer 10

 At the end of normal expiration = - 4 mmHg (= 756 mmHg)
 At the end of normal inspiration = - 6 mmHg (= 754 mmHg)
 At deep inspiration -30 mmHg
 It is always -ve (subastmospheric)

Question 11

Explain the importance of the intra-pleural pressure. What happens when it increases pathologically?

Answer 11

1) Prevents lung collapse
2) Helps respiratory movements
3) ↓ work of breathing
4) Helps venous & lymphatic return
5) Index of lung elasticity
—————————————–
↑ intrapleural pressure → IPP = atmospheric Pressure = intraalveolar pressure→ loss of pressure Gradient → collapse

Question 12

Measurement of intrapleural pressure

Answer 12

By: intraoesphaged balloon connected to a sensitive manometer

Question 13

Describe pneumothorax, its types, causes and effects.

Answer 13

*Definition: air in the intrapleural space
*Types & causes:
1- Internal (closed spontaneous):
due to rupture of alveoli into the pleural space, e.g. severe cough in T.B
2- External (opened= traumatic):
due to injury of chest wall e.g. trauma, stab wound.
* Effects:
1. Collapse of lung = atelectasis
2. Distension of chest wall
3. Shift of mediastinum to opposite side

Question 14

Describe transmural pressures of the respiratory system

Answer 14

1- Transpulmonary pressure
It is the distending pressure of alveoli (lungs)
= alveolar pressure – pleural pressure = (760) – (756) = 4mmHg
2- Transthoracic pressure
It is the compressing pressure of the chest
= intrapleural pressure - atmospheric pressure = (756) – (760) = -4mmHg

Question 15

List and describe the action and the importance of the muscles acting during normal breathing, and those acting during deep breathing

Answer 15

Main inspiratory Muscles
1-  Diaphragm:
Supplied by phrenic nerve. (C3,4,5)
It causes 75% of the increase in chest size
2- External intercostal muscles:
Supplied by intercostal nerves

Question 16

List and describe the action and the importance of the muscles acting during normal breathing, and those acting during deep breathing

Answer 16

Main inspiratory Muscles
1- Diaphragm:
Supplied by phrenic nerve. (C3,4,5)
It causes 75% of the increase in chest size
2- External intercostal muscles:
Supplied by intercostal nerves
- Elevation (up) of ribs→↑ transverse diameter of chest
- Eversion (forward) of ribs→↑anteroposterior diameter of chest

Question 17

List and describe the action and the importance of the muscles acting during deep breathing

Answer 17

Accessory inspiratory Muscles:
1-Sternomastoid muscles
2- scalenus muscles
3-Serratus anterior
Expiratory muscles:
1- Internal intercostal muscles
2- Abdominal muscles

Question 18

Describe the mechanics of quiet breathing

Answer 18

Inspiration:
- Active
- By contraction of main inspiratory muscles
Expiration:
- Passive
- By relaxation of main inspiratory muscles & elastic recoil
of lungs

Question 19

Describe the mechanics of deep respiration

Answer 19

Deep inspiration:
- Active
- Strong contraction of diaphragm & external intercostal
muscles + contraction of accessory inspiratory muscles
Deep expiration:
- Active
- Contraction of abdominal & internal intercostal muscles

Question 20

Explain the effects of cutting of the spinal cord above C3…

Answer 20

→ paralysis of diaphragm → death

Question 21

Explain the effects of paralysis of external intercostal muscles on respiration.

Answer 21

no marked effect on normal breathing

Question 22

Explain the effects of cutting of the spinal cord below C5…

Answer 22

→ paralysis of external intercostal muscles + paralysis of all body skeletal muscles + no paralysis of diaphragm → no marked effect on normal breathing